5^3x-1 * 25^7-5x = 0.2 ^- степень
5^3х-1 * 25^7-5х = 0.2; 5^3х-1 * 5^14-10х = 5^-1; 5^-7х+13 = 5^-1; -7х+13 = -1; -7х=-1-13; |(-1); 7х=14; х=2;